Alignment systems in games are attempts to codify the moral
and ethical attitudes of characters into handy labels that can be used with the game mechanics. In other words, to separate the spectrum
of human behaviour into black and white. This provides a handy way to get a handle on conflict in the game. If you're Good, you fight Evil.
Often this extends as far as, "If it's Evil, it's okay to kill it."

In reality, of course, there are all sorts of shades to conflict.
If you're running a game with an alignment system, try setting up some Good characters who actually oppose what your (presumably Good) PCs
are trying to do. Build conflict not only around the obvious Evil Threat, but also within the factions that ostensibly support what
the PCs are doing.

But be careful. If you go too far with this, you risk turning your game into the Council of Elrond.

Transcript

Obi-Wan: Chancellor Palpatine, do you have any comment?Palpatine: His story is clearly ridiculous; he's utterly delusional.Anakin: Chancellor, it's worse than that. He's a Sith Lord. He's deliberately sowing mistrust and discord.Anakin: I'll put an end to his deceit! {attacks}Obi-Wan: Oh good grief.Count Dookû: Master Yoda is not 'ere to save you zis time, impetuous fool.Anakin:You're the impetuous fool!Count Dookû: Ah, such naïve joie de vivre. You and mah son would get along famously. Both such romantics. Soon you will see ze world is shades of grey, not black and white.Anakin: No! It is black and white! I've been surrounded by darkness since I was born.Anakin: And there will be no more black!Obi-Wan: <sigh> I'm really coming around to the idea of settling things with a Force Arm-Wrestle.